1. Field of the Invention
The invention relates in general to solid freeform fabrication and, in particular, to an infiltration technique that alters the appearance of a three-dimensional object formed by a solid freeform fabrication apparatus.
2. Description of the Prior Art
Recently, several new technologies have been developed for the rapid creation of models, prototypes, and parts for limited run manufacturing. These new technologies are generally called Solid Freeform Fabrication techniques, and are herein referred to as xe2x80x9cSFF.xe2x80x9d Some SFF techniques include stereolithography, selective deposition modeling, laminated object manufacturing, selective phase area deposition, multi-phase jet solidification, ballistic particle manufacturing, fused deposition modeling, particle deposition, laser sintering, and the like. Generally in SFF techniques, complex parts are produced from a modeling material in an additive fashion as opposed to conventional fabrication techniques, which are generally subtractive in nature. For example, in most conventional fabrication techniques material is removed by machining operations or shaped in a die or mold to near net shape and trimmed. In contrast, additive fabrication techniques incrementally add portions of a build material to targeted locations, layer by layer, in order to build a complex part. SFF technologies typically utilize a computer graphic representation of a part and a supply of a building material to fabricate the part in successive layers. SFF technologies have many advantages over conventional manufacturing methods. For instance, SFF technologies dramatically shorten the time to develop prototype parts and can produce limited numbers of parts in rapid manufacturing processes. They also eliminate the need for complex tooling and machining associated with conventional subtractive manufacturing methods, including the need to create molds for custom applications. In addition, customized objects can be directly produced from computer graphic data in SFF techniques.
Generally, in most SFF techniques, structures are formed in a layer by layer manner by solidifying or curing successive layers of a build material. SFF techniques generally fall into the following sub-categories: stereolithography, selective deposition modeling, laminated object manufacturing, and laser sintering. For example, in stereolithography a tightly focused beam of energy, typically in the ultraviolet radiation band, is scanned across a layer of a liquid photopolymer resin to selectively cure the resin to form a structure as described in, for example U.S. Pat. No. 4,575,330 to Hull. Somewhat similar to stereolithography is selective laser sintering where heat generated from a laser is used to fuse powder particles together to form an object in a layer by layer manner, as described in, for example U.S. Pat. No. 4,863,538 to Deckard. In one form of laminated object manufacturing objects are constructed by the successive deposition of thin layers of metal or plastic powder which is compressed and then sintered with a laser as described in, for example, U.S. Pat. No. 4,762,352 to Feygin. In another form of laminated object manufacturing, successive sheets of a plastic substrate are adhesively bonded in layers with a solvent as described in U.S. Pat. No. 6,324,438 to Cormier. In Selective Deposition Modeling, herein referred to as xe2x80x9cSDM,xe2x80x9d a build material is typically jetted or dropped in discrete droplets, or extruded through a nozzle, in order to solidify on contact with a build platform or previous layer of solidified material in order to build up a three-dimensional object in a layerwise fashion. Other synonymous names for SDM which are used in this industry are solid object imaging, solid object modeling, fused deposition modeling, selective phase area deposition, multi-phase jet modeling, three-dimensional printing, thermal stereolithography. selective phase area deposition, ballistic particle manufacturing, fused deposition modeling, and the like. Ballistic particle manufacturing is disclosed in, for example, U.S. Pat. No. 5,216,616 to Masters. Fused deposition modeling is disclosed in, for example, U.S. Pat. No. 5,340,433 to Crump. Three-dimensional printing is disclosed in, for example, U.S. Pat. No. 5,204,055 to Sachs et al. Often a thermoplastic material having a low-melting point is used as the solid modeling material in SDM, which is delivered through a letting system such as an extruder or print head. One type of SDM process which extrudes a thermoplastic material is described in, for example, U.S. Pat. No. 5,866,058 to Batchelder et al. One type of SDM process utilizing a printer to selectively dispense a liquid binder on a layer of powder is described in, for example, U.S. Pat. No. 6,007,318 to Russell, et. al. One type of SDM process utilizing ink jet print heads is described in, for example, U.S. Pat. No. 5,555,176 to Menhennett et al. Some thermoplastic build materials used in SDM are available and sold under the names ThermoJet(copyright) 2000 and ThermoJet(copyright) 88 by 3D Systems, Inc. of Valencia, Calif. Also, some formulations for thermoplastic phase change build materials are disclosed in U.S. Pat. No. 6,132,665 to Bui et al.
Recently, there has developed an interest in utilizing curable phase change materials in SDM. One of the first suggestions of using a radiation curable build material in SDM is found in U.S. Pat. No. 5,136,515 to Helinski, wherein it is proposed to selectively dispense a UV curable build material in an SDM system. Some of the first UV curable material formulations proposed for use in SDM systems are found in Appendix A of International Patent Publication No. WO 97/11837, where three reactive material compositions are provided. More recent teachings of using curable materials in three-dimensional printing are provided in U.S. Pat. No. 6,259,962 to Gothait and in International Publication Number WO 01/26023.
However, one inherent drawback of using curable build materials in SFF techniques such as stereolithography and selective deposition modeling is the inability to produce objects exhibiting a wide variety of colors. For instance, coloring agents introduced into a UV curable resin tend to block the penetration of UV radiation necessary to solidify the material. Thus, in order to produce colored objects, it is often necessary to manually paint the surface of the objects to the appropriate color after they have been formed by an SFF apparatus.
Thus, there is a need to develop an improved method to change the appearance of objects formed by SFF. These and other difficulties of the prior art have been overcome according to the present invention.
The present invention provides its benefits across a broad spectrum. While the description which follows hereinafter is meant to be representative of a number of such applications, it is not exhaustive. As will be understood, the basic methods and compositions taught herein can be readily adapted to many uses. It is intended that this specification and the claims appended hereto be accorded a breadth in keeping with the scope and spirit of the invention being disclosed despite what might appear to be limiting language imposed by the requirements of referring to the specific examples disclosed.
It is one aspect of the present invention to process objects formed by any solid freeform fabrication apparatus so as to introduce an infiltration agent capable of altering the appearance of the objects.
It is a feature of the present invention to process objects formed by any solid freeform fabrication apparatus by submersing the object in a fluid containing an infiltration agent at a temperature above the glass transition temperature (Tg) of a polymer component of the object.
It is an advantage of the present invention that objects formed by any solid freeform fabrication technique containing a polymer material can be infiltrated with a colorant.
These and other aspects, features, and advantages are achieved/attained according to the present invention of producing a visually altered article initially formed by a solid freeform fabrication apparatus. The method comprises:
applying a fluid medium to the three-dimensional object at a temperature above the glass transition temperature of the polymer component, the fluid medium carrying an infiltration agent and permeating the three-dimensional object at a temperature above a glass transition temperature of the polymer component;
maintaining the application of the fluid medium to the three-dimensional object for a desired period of time to allow the infiltration agent to penetrate the three-dimensional object and establish a desired appearance of the three-dimensional object; and
terminating the application of the fluid carrying the infiltration agent to the three-dimensional object.
A fluid composition for use in altering the appearance of three-dimensional objects comprises an oil-based component and infiltration agent. The oil-based component permeates the three-dimensional object when in contact with the three-dimensional object at a temperature above a glass transition temperature of the polymer component in the object. The infiltration agent is dispersed in the oil-based component and penetrates the three-dimensional object during processing to alter the appearance of the three-dimensional object.